The president and prime minister in Tunisia's day-old interim government have left the RCD party - a symbol of the old regime reviled by protesters.
Prime Minister Mohammed Ghannouchi insisted his government had "clean hands", but said the transition needed experienced politicians.
Protesters want the RCD disbanded, and say no members of the old regime should retain power.
Three ministers quit the government earlier over the RCD's involvement.
Opposition groups view the RCD (Constitutional Democratic Rally) as synonymous with hardline former President Zine al-Abedine Ben Ali, who was forced from power on 14 January.
State-run television reported that the prime minister and president were leaving the RCD to "split the state from the party".
Interim President Foued Mebazaa was the speaker of the country's parliament until Mr Ben Ali was forced to flee the country.
Mr Ghannouchi, who unveiled the national unity government on Monday, is a veteran RCD figure, and has been prime minister since 1999.
The RCD also expelled Mr Ben Ali from its ranks, according to state TV.
Earlier, three ministers from the opposition General Union of Tunisian Workers (UGTT) stepped down from the new administration over the issue.
Officials from the UGTT said the trio - junior transport minister Anouar Ben Gueddour and two other ministers, Abdeljelil Bedoui and Houssine Dimassi - were resigning in protest.
Mr Ghannouchi's choice as health minister, Mustafa ben Jaafar from the Union of Freedom and Labour, later refused to take up his position in the government.
But analysts say he is known as a moderate, and may be tempted back into the administration by the actions of the leaders.
'Era of freedom'
On the streets of Tunis and several other cities, angry demonstrators called for those members of the RCD still in power to step aside, and were strongly critical of Mr Ghannouchi.
"I am afraid that our revolution will be stolen from me and my people," Ines Mawdud, a 22-year-old student, told the Associated Press.
"The people are asking for freedoms and this new government is not. They are the ones who oppressed the people for 22 years."
Despite the resignations and street protests, a number of ministers were sworn in on Tuesday in official ceremonies in Tunis.
Opposition figure Najib Chebbi, founder of the opposition Progressive Democratic Party, took up his position as development minister.
Prominent blogger Slim Amamou, who was briefly jailed by President Ben Ali's police, was also sworn in as secretary of state for youth and sports.
Earlier, Mr Ghannouchi defended the inclusion of members of the old regime in his new government.
"We have tried to put together a mix that takes into account the different forces in the country to create the conditions to be able to start reforms," he said.
He said some politicians from the previous government were needed to help steer the country towards elections, which he said would be held within six months.
After the resignations, UN Secretary-General Ban Ki-moon renewed his call for "broad-based consultations to establish an inclusive interim government".
Unrest in Tunisia grew over several weeks, with widespread protests over high unemployment and high food prices pitching demonstrators against Tunisia's police and military.
On Monday the government admitted 78 people had died in street clashes.